having fronds or parts of fronds that dry and fall from the rhizome or axis during the seasons unfavourable for growth; applied to most temperate and cold climate ferns and to some tropicalspecies that grow in seasonally dry regions. (syn.deciduous ).

the separation of major plant parts such as fronds from rhizomes or pinnae from rachises as a result of natural structural and chemical changes (see abscission layer). These changes can be a consequence of natural ageing (senescence ) or a response to desiccation or disease. (cf.abscissent; senescence ).

an often evanescent spot, swelling, or finger-like projection of thin-walled cells found along the stipe or in the pinna or pinnule axils of some ferns, especially Thelypteridaceae, that apparently aids gas exchange with the atmosphere. (cf.hydathode ).

(1) an area enclosed by a ring of veins and with or without one or more freeincluded veinlets; (2) also used to describe spore onamentation in which areas of the spore surface are enclosed by muri (see retate ).

like a chain composed of links; in hairs, with adjacent cells collapsed at right angles to each other and often the end walls of the cells thickened or dark-coloured, as on some Ctenitis fronds. (syn.ctenitoid, jointed ).

a general term for a shallow, steep-sided, indentation (crater); usually applied to spore ornamentation and the basis of several more specialized terms such as foveate and foveolate . (pl.cavi ; cf.bulla, murus, stela ).

(1) similar in shape and size to others, commonly applied to an apicalpinna in comparison with the lateralpinnae . (ant.difform); (2) having all cells of the body similar in shape and orientation, as the rhizome scales of Sphaeropteris. (cf.marginate ).

bearing small teeth formed by prolongations of one or two cells of the scalemargin as in some Diplazium; also said of clathrate scales in which the end walls of the marginal cells are thickened and so appear to be teeth, as in Aspleniaceae.

(1) in relation to frond complexity: a pattern of branching in which there are only two branches at each fork and the two branches are equal (more-or-less) in size, shape, and position, such as in Psilotum (n.dichotomy ; cf.pseudodichotomous); (2) in relation to venation: a branching pattern in which the two veins resulting from each fork are free and more-or-less equal. (n.dichotomy ; cf.pinnate )

the outermost layer of cells of the plant that lacks intercellular spaces, contains stomates, and serves to protect the plant, to selectively exchange gases, and to retard water loss by producing a wax-like cuticular layer or by being impregnated with a wax-like substance. (adj.epidermal).

a typically descriptive or commemorative word, usually an adjective but sometimes a noun in apposition, that is combined with the name of a genus to form the name of a taxon, or with the name of a species to form the name of an infraspecific taxon.

vertical or upright from within the substrate, often producing a cluster of fronds in a basket or shuttlecock-like arrangement, with approximatestipe bases on all sides. (cf.ascending, repent (creeping)).

(1) completing its growth cycle in a short period of time, such as species adapted to seasonally wet habitats. (2) said of structures that are conspicuous for a short period and then disappear, such as the aerophores of some species.

having a white, yellow, or other coloured, usually thick, powdery-appearing exudate of glands, especially on the underside of the lamina in Pteridaceae. (n.farina; syn.ceraceous; cf.glaucous, pruinose).

a popular but outdated term used for a paraphyletic assemblage of spore-bearing (seedless) vascular plants that were all believed to be closely related to true ferns. The term referred to horsetails, whisk ferns, quillworts, clubmosses and spikemosses. Nowadays, horsetails and whisk ferns are regarded as true-ferns (monilophytes) and the quillworts, clubmosses and spikeworts (now collectively called lycophytes) are believed to be very distantly related to these. (cf.lycophytes, monilophytes, pteridophytes).

a rank of taxa subordinate to the species and used for minor variants, such as different colour forms, that are scattered throughout the geographic range of the species; commonly the lowest category in the hierarchy of infraspecific taxa.

having the surface very thinly covered and not obscured by a bluish or whitish, wax-like coating, such as the laminae of some Cyathea, Microlepia, Selliguea and Dennstaedtiaceae species (cf.farinose, pruinose).

in the Gleicheniaceae and some Dennstaedtiaceae, a bud borne at the apex of an axis that is flanked by two branches; eventually it may break dormancy and elongate, most commonly extending the rachis of the frond. (cf. dormant bud).

a section of an elongate structure, such as a rhizome or stipe, or a planate structure such as a lamina, that is parallel to the principal axis of the structure. If the section passes along and through the principal axis then it can also be called a radial section; if the section is to one side of the principal axis and therefore does not go through that axis then it can also be called a tangential section.

a group of spore-bearing (seedless) vascular plants that, in terms of their reproductive biology, are similar to ferns but are not closely related to ferns. Lycophytes are the oldest extant group of vascular plants appearing some 50 million years before the first ferns. The group includes quillworts, clubmosses and spikemosses. (cf.monilophytes; fern-allies; pteridophytes).

a self-perpetuating, commonly tetrahedral cell or a region of cells that are thin-walled and mitotically dividing and that produce cells which will develop and differentiate into various tissues and structures.

(1) the point on a stem where leaves and branches are borne, especially in Equisetum, or the point on a rhizome where one or more fronds are borne; (2) a discoloured, swollen, or articulate area on the stem of some Selaginella or on the stipe of some ferns, especially Danaea; (3) the attachment points of the sheaths along the stems of Equisetum. (adj.nodose).

a rank of taxa above family and below class; the totality of families that are more closely related to one another than they are to any other families of other orders. Sometimes a single, markedly distinct family also constitutes an order.

incised nearly all the way to the axis (or, ar least, more than half way to the axis), with the segments still partially attached, laterally, to neighbouring segments. (cf.lobate, pinnate, pinnatisect).

the taxonomic group (Division) that contains all the vascular plants that bear spores instead of seeds: i.e. monilophytes (ferns, now including horsetails and whisk ferns) and lycophytes (quilllworts, clubmosses and spikemosses). In some classifications Pteridophyta is considered a subdivision of Tracheophyta (the Division that contains all vascular plants). (syn. Pteridophytes, "Ferns & Fern Allies").

in modern usage, a synonym of ferns. In traditional usage, the term was the equivalent of Pteridophyta (or “ferns and fern-allies”) and therefore referred to all the vascular plants that bear spores instead of seeds. i.e. ferns, horsetails and whisk ferns (now all regarded as true ferns) and quillworts, clubmosses and spikemosses.

in the Marattiales, a swollen, node-like region at the base of a stipe or costa that loses or gains turgidity under different conditions of hydration and consequently causes fronds or pinnae to collapse or regain their normal position.

growing in a location that is frequently but not permanently exposed to fast running water, such as on or between rocks along riverbanks or on islands in rivers. (n.rheophyte; cf.amphibious, aquatic, terrestrial )

a very thin, recumbent or prostrateroot-like or stem-like structure that lacks small, leaf-like appendages but forms new plants along its length or at its tip, as in Nephrolepis. (pl.sarmenta; cf.stolon).

a hard, elongate, sharp-pointed projection, found especially in certain species of Cyatheaceae, Dennstaedtiaceae, and Marattiaceae. Corticinate spines arise from the cortex; squaminate spines are the thickened, central portion of an elongatescale at maturity with the thin marginal portion worn away. (adj.spiny; adj.dim.spinulose; n.dim.spinule).

diverging ever more strongly in different directions, and so greatly separated distally one from another, as the labia of the involucres of some Hymenophyllaceae or the scales on some rhizomes and stipes. (syn.flared; cf.divaricate, divergent).

star-shaped; applied to hairs and scales. Simplestellate hairs are branched above the base (from the apex of the pedicel) into three or more usually equal rays (see, for example, the hairs on the lamina of Pyrrosia, Platycerium and some Grammitidaceae). Twice-stellate hairs are forked or branched above the base (from the apex of the pedicel) into two or more arms, with each arm branching into three or more usually equal rays (see, for example, the hairs on the stipes and laminae of some Hymenophyllaceae); Stellate scales bear several broad to narrow teeth, usually of unequal size, from a relatively large central point (see, for example, the scales on the lamina of some Aspleniumspecies). (cf.bifurcate, twice-bifurcate).

(1) in the Marattiaceae, each one of a pair of lateral, fleshy, starch-bearing, persistent, partially or entirely vascularized outgrowths of the rhizome that clasp the base of the stipe and that are capable of reproducing the plants vegetatively; (2) in the Ophioglossaceae, merely the remnants of the older stipebase that originally enclosed and protected the younger, less developed fronds.

a minute, epidermal pore bordered by a pair of relatively large and conspicuous (under the microscope) guard cells and often a usually uniform array of subsidiary cells that differ from the adjacentepidermal cells. (pl.stomata; syn.stomate).

one of two or more names for the same taxon; if based on the same type (homotypic), they are considered to be nomenclatural synonyms; if based on different types (heterotypic), they are considered to be taxonomic synonyms.

any one of two or more specimens used and cited by the author to prepare the diagnosis or description, when no holotype was designated. One of the syntypes may be selected to be a lectotype by a later author, but the “rejected” syntypes do not become paratypes, they remain syntypes.